The present invention relates to a headlight for vehicles. More particularly, it relates to a headlight having a reflector and a light source, wherein the reflector in axial longitudinal sections has substantially ellipsoidal section curves.
Such a headlight is disclosed for example in the German document DE 33 34 459 A1. The headlight has a reflector which in its axial longitudinal sections has section curves formed as ellipses. The first focal points of the ellipses substantially coincide, and the incandescent coil of an incandescent lamp is arranged in this region. A screen [aperture] is spaced from the reflector apex in a light direction, and a lens is spaced from the screen in the light direction. The second focal point of the ellipse produced in the vertical longitudinal section by the reflector is located in the region of the screen. The second focal point of the ellipse produced in the horizontal longitudinal section by the reflector is located in the region of the lens. The upper edge of the screen is projected through the lens as a bright-dark limit in the light intensity distribution produced by the headlight.
In new headlights, gas discharge lamps are utilized as light sources instead of the incandescent lamps. They provide a substantially higher intensity light stream and have a longer service life. With the utilization of a light source which has a higher light intensity when compared with an incandescent lamp, such as a gas discharge lamp, the headlight known from the German reference DE 33 34 459 A1 causes, due to the radiation characteristic different from that of an incandescent lamp, undesired non-uniformities in the light intensity distribution produced by the headlight. Moreover, the radiation range maximum is located not in the center of the light intensity distribution, but instead is offset laterally to it and is so high that the maximum light intensity values which are prescribed in accordance with corresponding regulations are exceeded. Generally speaking, this headlight is therefore not suitable for the use of a light-intense light source.